Sitting in front of a tall mirror in a swish Beverly Hills home, Mr Somerhalder squints at his reflection and musses his hair while a make-up guy called Charles dabs around his eyes.

"Oh the tattoo?" he says, pointing at the inscription on his forearm: Hic et nunc. "It means 'I am hung' in Latin. Ha ha! No, I'm kidding. It means 'here and now'. But I've said that to people, and they believed me."

He's best known as Damon Salvatore from The Vampire Diaries, a raging hit among panting teenage girls (who call him "Smolderholder" on their blogs). The rest of us may recognise him from Lost.

Today, however, he is "the talent" on a photoshoot, a role that he embraces. Despite the hubbub of a full crew setting up for the shoot, only one voice cuts through it all - he's the loudest and most confident person in the room. And he doesn't stop talking. Some stars might retreat behind their handlers, but Mr Somerhalder would rather introduce his handlers to everyone in person.

"This will revitalise it," he says, pointing to a tub of hair product. He turns his head, examining his reflection. "It won't make it greasy, it'll give you a great base."

Charles checks the label. "Yeah, this gets right into the hair."

"OK use it. Go for it baby."

All actors are familiar with the make-up chair, but few are quite this comfortable. Mr Somerhalder, however, has been modelling since he was 10. He spent his teens travelling the world and "working it" for the cameras, an extraordinary life by any standard. But the way he tells it, he's just a simple boy from the South - specifically, a small town called Covington near New Orleans, Louisiana. His mum was a massage therapist and his dad a building contractor. They didn't have much, but life was idyllic nonetheless.

The mid-1990s were like this total Dionysian, promiscuous time in the fashion business. An amazing time to be young and not have any responsibility

"Dude, look." He starts scrolling through shots on his iPhone of the bayou near his family home. "That's my nephew on the boat. We're teaching him how to paddle. I did exactly the same thing at his age. Total Louisiana stereotype, with the crawfish boiling in the pot, you know? We had a rope swing and we'd jump off right into the water."

There's not a drop of gumbo in his accent through. You'd never peg him for a Southerner. His mum knew he'd be an actor, and a drawl wouldn't help him, so she "used every dollar we had to put me into acting classes," he says. "Losing the accent takes away that first initial... People are extraordinarily judgmental."

He soon escaped the conservative South for New York, where he has lived since the early 1990s. As a young model, he and his mother would visit the big city for the summer, renting a tiny apartment that "cost more per month than any house we ever lived in". But even at the age of 11, he was earning a proper wage. And on his 16th birthday - on 8 December 1994 - it became a lot more proper. The photographer Mr Steven Meisel saw a Polaroid of his and decided to put him in a 12-page story in L'Uomo Vogue. Pretty soon photographers such as Mr Bruce Weber were calling. And within a year, he was living between Milan, Paris and New York.

"Yeah, it was nuts," he says. "The mid-1990s were like this total Dionysian, promiscuous time in the fashion business. An amazing time to be young and not have any responsibility.

the work

Lost

The actor in season six of the TV series, with on-screen
stepsister played by Ms Maggie Grace

pulse

the tournament

Mr Somerhalder played an assasssin in the 2009 British indie film

the vampire diaries

Mr Somerhalder in series three with co-star Ms Nina Dobrev

Ultimately, though, he found fashion unfulfilling, and turned to acting. And when the big break came with Lost, it was snatched away almost as suddenly as it arrived. He was the first to be cast and the first to be killed off. He'd been on the show for a year when he received the call from the show creators.

"It was brutal. Not only are you losing this amazing job, but you're losing this family on set. Luckily, I was in wine country!"

A girl called Jessica arrives with a draft of a press release for his approval. It's something about an award, but lately, Mr Somerhalder has had a lot of those, mostly from the Teen Choice people - he was recently voted Choice Male Hottie, for instance.

But this is different. Jessica is reading phrases such as "empowering and educating" and "sustainable agriculture". Apparently, when this shoot is over, he will be whisked off to the Environmental Media Association awards to be honored for the Ian Somerhalder Foundation that promotes environmental and animal rights causes.

"I started it in 2010 in response to the BP oil spill," he says. "I remember watching President Obama just step aside and let BP do whatever it wanted because it was a big contributor to his campaign. And I felt so powerless, I realised I never wanted to feel that way again."

With the support of his mentor Mr Deepak Chopra, among others, the foundation was born. He's presently in the throes of buying a farm in Louisiana that he wants to turn into an animal sanctuary.

But first, he has the fourth season of The Vampire Diaries to shoot. So after the awards show, he'll be back on a plane to the set in Atlanta. And beyond that? Well, there are all these rumours whirling about Fifty Shades of Grey. Apparently, his name is one of those under consideration for the role of Christian Grey, the billionaire bondage-master.

"Oh man, there's nothing official," he shrugs. "It's just talk."

So has he been getting into a bit of S&M in the meantime, just in case he gets the call?

"Yeah, there's a website you can go to where you can just outfit your basement as a dungeon," he says, springing out of his chair and giving his reflection one last check. "So, you know, I thought I'd get prepared, just in case."

He's turning his basement into a dungeon?

He grins. "Totally. I think a lot of people are doing that right now!"